1. Field
Example embodiments of inventive concepts relate to a microelectromechanical system (MEMS) manufactured by using a substrate etching and bonding method, and more particularly, to a MEMS for a terahertz oscillator manufactured by bonding a plurality of etched substrates.
2. Description of the Related Art
A terahertz band is useful with respect to applications of molecular optics, biological physics, medical science, spectroscopy, image processing appliances, and security appliances. Though the terahertz (1012 Hz) band ranges from the microwave band to the optical band, there are only a few currently developed oscillators and amplifiers operating with respect to the terahertz band due to various physical and engineering limitations. Recently, such terahertz band oscillators or amplifiers have been developed by using diverse new concepts and an advance in micro processing technology.
A variety of approaches have been attempted to increase the frequency at which existing microwave band oscillators operate or to lower the operating frequency of oscillators operating within a higher frequency band to be within a terahertz band by using optical instruments such as a semiconductor laser or a femtosecond laser. Furthermore, various attempts have been made to fabricate a compact size terahertz oscillator.
Among the attempts, there has been developed a method of forming a three-dimensional (3D) microstructure on a substrate by using MEMS technology.
In particular, in a structure having a step height of 100 to 1,000 μm, because etching plasma, such as by way of deep reactive-ion etching (DRIE), may not uniformly permeate into the deep step, desired precision and uniformity may not be achieved. On an etched bottom surface, an etching rate is different near edges, generating a radius of curvature.
In addition, etching rate changes with depth, making it difficult to accurately perform etching to a desired depth. Moreover, an edge may have a radius of curvature, increasing a deviation in depth in the etched bottom surface. This phenomenon becomes more serious as etching depth increases.